Fluorine-containing alkyl iodides have a broad range of industrial applications. Fluorine-containing alkyl iodides can be prepared by thermal and redox-induced telomerizations of olefins with linear or branched perfluoroalkyl iodides. The thermal telomerizations are typically conducted at temperatures greater than about 200° C. at high pressures and usually lead to mixtures of homologue telomers in the product requiring sequential separation. Expensive specialized equipment is required to conduct the telomerization at such high temperatures and pressures. If lower temperatures are employed, then the conversion rate drops to unacceptable levels. Telomerization reaction of addition of an olefinic compound to perfluoroalkyl iodides in the presence of a free radical initiator solution also leads to mixtures of telomere products and sequential separation of the products is required.
It has been reported by Qing-Yun Chen, et al., in Journal of Fluorine Chemistry 36 (1987) 483-389, that polyfluoroalkyl iodides can be prepared at a lower temperature of about 80-100° C. by the telomerization reaction of perfluoroalkyl iodides with a fluorinated olefinic compound such as tetrafluoroethylene, in the presence of a copper catalyst. However, it has been discovered that copper catalyst does not work efficiently in some olefin addition or insertion reactions, especially in such reactions wherein the olefinic compound is vinylidene fluoride.
In connection with ethylene addition reactions, processes employing ruthenium/activated carbon (Ru/C), platinum/activated carbon (Pt/C), silver/alumina (Ag/Al2O3), and like noble metals as catalysts are reported by Konrad von Werner in Journal of Fluorine Chemistry 28 (1985); 229-233. However, use of the noble metals has the disadvantage that they are expensive and thus result in high production costs. Further some such catalysts are not readily available commercially and are difficult or toxic to prepare.
It is desirable to have a process for the insertion of an olefin into a fluoroalkyliodide which can be conducted at a lower temperature than the traditional thermal processes using a readily available inexpensive catalyst at an acceptable conversion rate with good selectivity for particular homologue telomer products. The present invention provides such a process for the preparation of a fluoroalkyl iodide by the insertion of an olefin into the carbon-iodine bond of a fluoroalkyl iodide in the presence of a nickel derivative catalyst. The process of the invention is operated at a temperature from about 60° to 150° C.